Angular 4.0 http put请求 [英] Angular 4.0 http put request

问题描述

我编写了一个函数来发送http put请求以更新一些数据，但是它说，它没有接收到任何数据:

I've written a function to send a http put request to update some data but it says, that it is not recieving any data:

updateHuman(human: Human) {
    const url = `${this.url}/${human.id}`;
    const data = JSON.stringify(human);
    return this.http.put(url, data).map(
        response => response.json().data as Human,
        error => console.log(error)
    );
}

将功能更改为以下功能后，它可以正常工作:

After I've changed my function to the following, it is working:

updateHuman(human: Human) {
    const url = `${this.url}/${human.id}`;
    const data = JSON.stringify(human);
    return this.http.put(url, data).map(() => human);
}

有人可以解释一下，为什么第一个功能不起作用，而第二个功能却起作用吗?

Could someone explain me, why the first function is not working but second is working?

推荐答案

可观察对象是惰性的，您需要订阅它们才能使它们工作并检索任何内容.您订阅了您的方法吗?示例:

Observables are lazy, you need to be subscribed to them for them to work and retrieve anything. Did you subscribe to your method? Example:

methodToUpdateHuman(human): void{
...
this.updateHuman(human).subscribe((response) => {
   //do something with the response
   console.log.("Response is: ", response);
},
(error) => {
   //catch the error
   console.error("An error occurred, ", error);
});
}

我建议您通读英雄角度游，它基于角度2和大多数功能在angular 4中起作用，有专门用于http请求的部分: https://angular.io/tutorial/toh-pt6

I suggest you read through the Angular Tour Of Heroses, it's based in angular 2 and most of the functionality is functional in angular 4, there is a section dedicated to http requests: https://angular.io/tutorial/toh-pt6

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